Drill motors are commonly used for drilling, screwing, sanding and the like. Typically, drill motors include an electric or fluid motor mounted in a housing having a handle with a built-in trigger switch for actuating the motor when the drill motor operation is desired. The motor has a drive shaft projecting from it and the housing. A chuck assembly is mounted on the drive shaft and includes a locking drum cylinder and an inner cylinder. The inner cylinder threads on the drive shaft and the locking drum cylinder are concentrically mounted to the inner cylinder. A plurality of chuck jaws threadedly engage the locking drum to open or close in response to the locking drum being driven in clockwise or counter-clockwise directions. The chuck jaws grip and release the shafts of drill bit, screw bits, sanding tools and the like.
Prior art chuck jaws are adjusted to receive different size shafts by turning the locking drum with a bevel gear provided on a forward edge of the locking drum. The chuck jaws are manually opened or closed while the drive shaft remains stationary by inserting toothed portions and a pivot pin of a pivot key into the level gear and one of a plurality of equispaced pivot holes on the chuck inner cylinder.
Pivot keys have the disadvantage of often being lost or misplaced, particularly when used with portable tools. Another disadvantage of pivot keys is that not all chuck jaws have the same number of bevelled teeth, therefore, the pivot keys are not interchangeable between chuck assemblies. Some people have found pivot keys difficult to manipulate, due to arthritis, etc.
The advent of keyless chucks has not been totally successful. Some patented keyless chucks, for example, U.S. Pat. No. 4,095,811, issued to Cohen, requires the use of both hands to engage the chuck portion of a drill motor, making it necessary to balance the heavier drill motor during chuck manipulation. U.S. Pat. No. 4,460,296, issued to Silvertson, employs a gripping device for opening and closing jaws of a chuck Where a second portion of the device is urged into frictional or locking engagement. The locking cylinder in U.S. Pat. No. 4,317,578, issued to Welch, is locked to the drill motor housing by a trigger and pin assembly which engages a slot in the locking cylinder. This arrangement also requires two hand manipulation or supporting the drill motor, squeezing the trigger and aligning the drill bit; a somewhat awkward arrangement.
It is accordingly an object of the present invention to provide a new and improved keyless chuck gripping device that uses the rotation energy of a drill motor to bring about the manipulation of the chuck jaws for opening or closing said jaws.
Another object of the invention is to provide a keyless chuck with a switch for changing the motor speed to a predetermined torque for opening or closing the chuck jaws.
Still another object is to provide a keyless chuck locking sleeve device for locking a chuck assembly, in particular an outer chuck.
Yet another object is to provide a keyless chuck locking sleeve device which provides a positive locking engagement with the outer chuck of a chuck assembly.